Penrite 15w-50 in a TD ?

[Touses]

I'm also using the Penrite 15/50 semi synth.
I've found if I'm Miss Daisying, short runs to and from work etc, it will chew thru a bit.
The moment I load the backpack or start dragging the camper trailer that pretty much ceases.
The big whooer loves to work.